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Traditionally, Kong has always required a database, which could be either
Postgres or Cassandra, to store configured entities such as Routes, Services,
Starting with Kong Enterprise 2.1, Kong can be deployed in
Hybrid mode, also known as Control Plane / Data Plane Separation (CP/DP).
In this mode, Kong nodes in a cluster are split into two roles: Control Plane
(CP), where configuration is managed and the Admin API is served from; and Data
Plane (DP), which serves traffic for the proxy. Each DP node is connected to one
of the CP nodes. Instead of accessing the database contents directly in the
traditional deployment method, the DP nodes maintain connection with CP nodes,
and receive the latest configuration.
When you create a new Data Plane node, it establishes a connection to the
Control Plane. The Control Plane listens on port 8005 for connections and
tracks any incoming data from its Data Planes.
Once connected, every Admin API or Kong Manager action on the Control Plane
triggers an update to the Data Planes in the cluster.
Hybrid mode deployments have the following benefits:
- Deployment flexibility: Users can deploy groups of Data Planes in
different data centers, geographies, or zones without needing a local clustered
database for each DP group.
- Increased reliability: The availability of the database does not affect
the availability of the Data Planes. Each DP caches the latest configuration it
received from the Control Plane on local disk storage, so if CP nodes are down,
the DP nodes keep functioning.
- While the CP is down, DP nodes constantly try to reestablish communication.
- DP nodes can be restarted while the CP is down, and still proxy traffic
- Traffic reduction: Drastically reduces the amount of traffic to and from
the database, since only CP nodes need a direct connection to the database.
- Increased security: If one of the DP nodes is compromised, an attacker
won’t be able to affect other nodes in the Kong cluster.
- Ease of management: Admins only need to interact with the CP nodes to
control and monitor the status of the entire Kong cluster.
You can run Kong Enterprise in Hybrid mode on any platform where
Kong Enterprise is supported.
Kubernetes Support and Additional Documentation
Kong Enterprise on Kubernetes
fully supports Hybrid mode deployments, with or without the Kong Ingress Controller.
For the full Kubernetes Hybrid mode documentation, see
When a configuration change is made at the Control Plane level via the Admin
API, it immediately triggers a cluster-wide update of all Data Plane
configurations. This means that the same configuration is synced from the CP to
all DPs, and the update cannot be scheduled or batched. For different DPs to
have different configurations, they will need their own CP instances.
When plugins are running on a Data Plane in hybrid mode, there is no Admin API
exposed directly from that DP. Since the Admin API is only exposed from the
Control Plane, all plugin configuration has to occur from the CP. Due to this
setup, and the configuration sync format between the CP and the DP, some plugins
have limitations in Hybrid mode:
- Key Auth Encrypted: The time-to-live setting
ttl), which determines the length of time a credential remains valid, does
not work in Hybrid mode.
- Rate Limiting Advanced:
This plugin does not support the
cluster strategy in Hybrid mode. The
strategy must be used instead.
- OAuth 2.0 Authentication: This plugin is not
compatible with Hybrid mode. For its regular workflow, the plugin needs to both
generate and delete tokens, and commit those changes to the database, which is
not possible with CP/DP separation.
Custom plugins (either your own plugins or third-party plugins that are not
shipped with Kong) need to be installed on both the Control Plane and the Data
Plane in Hybrid mode.
Currently, there is no automated load balancing for connections between the
Control Plane and the Data Plane. You can load balance manually by using
multiple Control Planes and redirecting the traffic using a TCP proxy.